1. Field of the Invention
The present invention relates to acoustic input and output devices for a light conducting optical fiber.
2. Description of the Prior Art
In a conventional input device for an optical fiber, an input light beam is usually introduced into the fiber through its end face either directly or by way of an optical lens system. Such a conventional device suffers from the obvious drawback that the input light beam can only be injected into the optical fiber through an end face, and not at any intermediate location.
There is also a requirement for an optical fiber output device functioning as a mode analyzer or monitor. Two kinds of such output devices are known in the art. The first one extracts a propagating light beam by cutting a portion of the optical fiber where the output is wanted. Such a device is inconvenient since an output light beam cannot be extracted without cutting the optical fiber. In a second such device the optical fiber is machined down to a tapered shape at a desired location to implement the extraction of the propagating light beam. In the device the machining is difficult and troublesome, and the optical fiber cannot thereafter be restored to its original state.
Some correlated prior art in this technical field is listed below:
1. J. E. Fulenwider, U.S. Pat. No. 3,871,743 issued on June 4, 1973,
2. W. V. Smith, "IBM Technical Disclosure Bulletin" 14 No. 2, July 1971, p. 652,
3. E. G. Lean et al, U.S. Pat. No. 3,791,715 issued on Dec. 11, 1972, and
4. R. Ulrich, U.S. Pat. No. 3,905,676 issued on Sept. 16, 1975.